Nuclear Medicine's capability to present functional information has made it a valuable tool for clinical diagnosis and for biological research. It is desirable to improve system performance and various methods have been employed. Collimation techniques such as multiple pinholes or converging collimators can improve resolution for certain classes of study. Sensitivity can be improved with larger detector areas or diverging collimation. It is further useful if the imaging system can adapt to the actual source distributions of a specific case to optimize tomographic signal to noise by acquiring data selectively to dwell longer on source areas that contribute more information to the final image.
With some imaging methods gaps may appear in the angular sampling for portions of the object field. This type of reconstruction problem has been previously addressed in nuclear medicine. For example, fanbeam and conebeam collimators tend to produce truncated planar images that do not fully sample the sinogram.
Data acquisition methods for SPECT rely on a preset definition of dwell time, angular step, collimation and range of orbital sampling. These data acquisition protocols are variable as to type of study performed but are not case by case specific to the actual source distribution in a patient or subject of interest. As such they do not optimize the imaging results for a specific patient or subject of interest. Such data acquisition protocols can be non-uniform in their dwell time per step but are not varying due to the specific source distribution in an individual patient.